Technical Field
The present invention relates to the technical field of use of NADH, and particularly to use of NADH or a salt thereof in the preparation of drugs or health-care products for treating phenylketonuria (PKU).
Related Art
Nicotinamide adenine dinucleotide (NADH) is a coenzyme transferring protons (more precisely hydrogen ions), and involved in many metabolic reactions of cells. Nicotinamide adenine dinucleotide includes reduced nicotinamide adenine dinucleotide (NADH), which is also known as reduced coenzyme I; and oxidized nicotinamide adenine dinucleotide (NAD), which is also known as oxidized coenzyme I.
NADH is a fundamental redox coenzyme, which is key to both the respiration and the photosynthesis. Moreover, NADH cannot be directely oxidized by oxygen, but can become NAD by dehydrogenation under the action of NADH dehydrogenase. In the respiratory chain, through such an action, the flavoproteins, quinone, and cytochrome are gradually reduced, and finally oxygen is reduced into water. The pathway of oxidizing a substrate by O2 with NAD as a medium is a main oxidization pathway of organics in aerobic organisms. At present, the nicotinamide adenine dinucleotide (NADH) used in the circle of industries and medicines or as a biochemical agent is essentially produced through fermentation with yeasts or produced enzymatically in vitro.
The People's Daily Online reported (on Oct. 30, 2013) that there are over ten thousands children having phenylketonuria (PKU) in China, and PKU incurs great pain to the patients and their families. Under a normal condition, the proteins are intaken by human from food, and then broken down to produce various amino acids needed in the human body. Phenylalanine (Phe) is firstly metabolized into another amino acid tyrosine, and then into carbon dioxide and water through a series of metabolizations and excreted from the body. For the PKU patients, because the phenylalanine hydroxylase produced in liver cells is defective, its activity is decreased or lost almost completely, such that Phe cannot be metabolized into tyrosine. As a result, the in-vivo concentration of Phe is much higher than a normal level, and a too high Phe concentration in human is the main cause of dementia in patients with PKU. Natural proteins contain abundant phenylalanine in 1953, the doctor Bichel in Germany preferred a low phenylalanine diet therapy for treating the disease, and better results are obtained. However, the low-phenylalanine diet (also known as “specially supplied food”, or “special food”) is usually very expensive, thus causing a heavy financial burden and mental stress to an ordinary family. Moreover, the effect remains to be improved. An object of the present invention is to provide such a therapeutic agent or a health-care product.